JP3436648B2 - Waveform correction amplifier - Google Patents

Description

Description: BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to an RF signal amplifying apparatus that obtains a flat output regardless of the length of an input pause period. 2. Description of the Related Art FIG. 4 is a block diagram showing the configuration of a first conventional amplifying apparatus, and its RF output detection waveform and a timing chart of an amplifier drive signal. In the figure, 1 is an amplifier, 2 is a drive circuit for driving the amplifier, 3 is an RF input terminal to the amplifier, 4 is an RF output terminal, 5 is an external control signal for controlling the amplifying device, and 6 is on / off control of the amplifier. Is a drive signal, and 7 is an RF output signal detection waveform. Next, the operation of the apparatus having the above configuration will be described. The amplifier 1 is turned on / off by a drive signal 6 output from the drive circuit 2 in accordance with the external control signal 5. When the drive signal 6 is on, the amplifier 1
The RF signal input from the F input terminal 3 is amplified, and an RF output signal is output from the RF output terminal 4. The amplifier 1 generates heat when operating, that is, when the drive signal 6 is on, and generates heat.
At the time of non-operation, that is, at the time of off, no current flows and the temperature drops. In this conventional example, as the drive signal 6, a waveform having the same length according to the external control signal 5 is output as shown in a timing chart. The operation of the amplifier 1 is directly controlled by the drive signal 6, and the gain of the amplifier 1 generally varies depending on the voltage level of the drive signal 6. According to this configuration, the gain of the amplifier is stable in a state in which the gain of the amplifier has decreased due to temperature saturation except for the initial period of B ₁ and B _{2 in which} the period during which RFin is paused is short. However, if the immediately preceding idle period A _1, A _2, A ₃ is long, the gain since the temperature is lowered immediately after the amplifier is increased, as indicated by the RF output detection waveform in FIG. 4, B _1, A relatively large amplified output is obtained at the first part of B ₂ and B ₃ . As a second conventional example, a circuit for correcting the amplification characteristic of a high-frequency FET amplifier is disclosed in Japanese Patent Laid-Open No. 63-269815.
FIG. 5 describes the circuit of FIG. In the figure, 52 is a bias circuit, 53 is a pulse generation circuit, 54
Is an adder, 57 is a high-frequency FET as an amplifier, 56 is an input signal terminal, and 58 is an output terminal. Signals shown in (b) to (f) represent signals at corresponding locations of the same symbols on the circuit diagram. The operation of the above circuit will be described. The drive signal (b) is generated by the pulse generator 53 which is an amplifier drive signal earlier than the input of the input signal (e). At the same time, the bias signal (c) is generated by the bias circuit 52 (or the input signal may be input to the high-frequency FET with a delay from the generation of the bias circuit and the pulse generator). By doing so, the initial amplification degree of the high-frequency FET output (f) is suppressed, and a flat amplified output is obtained. [0007] Since the conventional amplifier or the waveform correction amplifier is configured as described above,
In the conventional example, the amplification rises because the internal temperature of the amplifier has decreased for the initial input after the input signal has been off for a long time, and then the internal temperature rises when the amplification operation starts. As a result, there is a problem that the amplification degree decreases and overshoot occurs due to the high initial amplification degree. Second
In the conventional example, the amplifier is always operated prior to the actual input, so that high-speed operation can be prevented. Further, since the degree of amplification is always guaranteed, overcompensation is rather made for continuous input, and there is a problem that the waveform of the subsequent high-frequency input may be deteriorated. SUMMARY OF THE INVENTION The present invention has been made to solve the above problems, and has as its object to obtain an amplifier that outputs a flat signal waveform by controlling an initial amplification degree in accordance with an input non-signal period. . [0009] A waveform correction amplifier according to the present invention comprises a dry amplifier based on ON / OFF of an external control signal.
Controls the amplification gain of high frequency signals by turning on / off the active signal
Monitor the off period of the external control signal
Off-period monitor circuit and the off-period monitored
If it is longer than the time, the drive signal ON signal rises
The correction circuit that smoothes the waveform and the waveform
And a drive circuit that suppresses the rise of the live signal.
Was . DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS First Embodiment Hereinafter, a waveform correction amplifier according to Embodiment 1 of the present invention will be described with reference to the drawings. FIG. 1 is a block diagram showing a configuration of a waveform correction amplifier according to the present embodiment, and a timing chart of an RF output detection waveform and a drive signal of the amplifier. In the figure, 1 is an amplifier, 2 is a drive circuit for driving the amplifier, 3 is an RF input terminal to the amplifier, 4 is an RF output terminal, 5 is an external control signal for controlling the amplifying device, and 6 is on / off control of the amplifier. Is a drive signal, and 7 is an RF output signal detection waveform. Reference numeral 8 denotes a correction circuit that corrects the drive signal waveform, and reference numeral 11 denotes an off-period monitor circuit that monitors the length of the off-period of the amplifier, and is a type of non-signal detection means that detects a non-signal period immediately before signal input. Next, the operation of the amplifier having the above configuration will be described. The off period monitor circuit 11 always monitors the external control signal 5. When the amplifier circuit off period is shorter than the preset time, the drive signal 6 is input to the amplifier 1 without correction, as in the first conventional example. Next, when the off-period becomes longer than a preset time, the off-period monitor 11 detects the off-period and applies a predetermined correction to the waveform of the drive signal 6 by the correction circuit 8. The contents of the correction are as follows, as shown in the example of the timing chart of FIG.
1 until the temperature rises and reaches a certain temperature
Waveform shaping such that the rising waveform of the drive signal 6 is blunted so as to suppress the increase in gain. After the OFF state has been continued for a long time, the temperature of the amplifier 1 has dropped and the gain has risen from the normal ON state. In this case, the voltage level applied to the amplifier 1 is reduced, and the gain is reduced. As a result, the gain is maintained in a normal state, and the output overshoot is eliminated. The correction is performed only when the off-period long enough to affect the temperature of the amplifier 1 continues for a long time, and the correction is performed even when the normal temperature is stable as in the second conventional example, and the output is disturbed. There is no effect such as making If the overshoot of the RF output detection waveform (RFout4) is to be corrected, the gain of the amplifier 1 may be positively increased only at that time.
This is an effective means for eliminating a delay in rising when the amplifier 1 is turned on from an off state due to a trapping phenomenon of electrons generated in a semiconductor after a long off period. A case where another circuit is used as the no-signal detecting means will be described. That is, when the operation of the amplifying device is performed in a certain pattern, the off-period monitor circuit 11 shown in FIG.
A similar effect can be obtained by providing a pattern identification circuit 12 for identifying the pattern of the external control signal 5 instead of. In FIG. 2, a pattern identification circuit 12 as another non-signal detecting means monitors an external control signal 5 in which a fixed combination of patterns is repeated. Then, the drive signal is corrected every time the correction is needed.
For example, as shown in the timing chart of FIG. 2, when the operation of the amplifier 1 is repeated four times in the ON state and there is a rest period thereafter, the pattern identification circuit 12 counts the ON state of the external control signal 5, and A correction is added each time at the beginning of the ON state. Embodiment 2 In the above embodiment, the case where the waveform correction is applied to only one amplifier has been described. Here, a case will be described in which amplifiers for performing such waveform correction are connected in multiple stages to constitute one amplifier. FIG. 3 is a diagram illustrating a configuration of the amplification device according to the present embodiment. In the figure, 1a, 1b, 1c are amplifiers, 28a, 28
b and 28c are drive and correction circuits, and 20 is a no-signal detection circuit. By configuring a multi-stage amplifying device with the amplifier whose waveform has been corrected in this way, the same effect as in the first embodiment can be obtained in the multi-stage amplifying device. In that case, one or more stages of the amplifier of the present invention are provided in the last stage or an arbitrary stage of the multistage amplifying apparatus, or all the stages are configured by the amplifier of the first embodiment. As described above, according to the present invention, since the no-signal detecting means is provided and the output of the amplifier controls the amplification degree of the amplifier, the output overshoot after a long period of inactivity or This has the effect of eliminating delays.

BRIEF DESCRIPTION OF THE DRAWINGS FIG. 1 is a block diagram showing a configuration of an amplifier according to a first embodiment of the present invention and a timing chart of an operation. FIG. 2 is a block diagram and a timing chart of an operation of another amplifier according to the first embodiment. FIG. 3 is a configuration diagram of an amplifier using multiple stages of a waveform correction amplifier according to a second embodiment. FIG. 4 is a block diagram and a timing chart of an operation of a conventional amplifying device. FIG. 5 is a block diagram and a timing chart of an operation of another conventional amplifying device. [Description of Signs] 1, 1a, 1b, 1c Amplifier, 2 drive circuit, 3
RF input signal terminal, 4 RF output signal terminal, 5 external control signal, 6 drive signal, 7 RF output detection waveform,
8 correction circuit, 10 amplifying device, 11 off-period monitor circuit, 12 pattern recognition circuit, 20 no-signal detection circuit (means), 28a, 28b, 28c drive and correction circuit.

Claims (1)

(57) [Claims 1] A driver based on ON / OFF of an external control signal.
The gain of high frequency signals is controlled by turning on / off the
The amplifier controlling the off period monitors the off period of the external control signal.
And capacitor circuit, the off period and the monitor above is longer than the predetermined time
Correction circuit to smooth the rising waveform of the drive signal ON signal
Suppressing the rise of the drive signal and the road, by the blunting allowed waveform
And a drive circuit .